Pension, Retiree Medical and Savings Plans (Categorized Plan Assets Measured at Fair Value) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 26, 2015	Dec. 27, 2014
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost Recognized		$ 164		$ 148	$ 130
U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		11,458		11,397	12,224
International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		2,894		2,823	3,002
US Plan Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1]	11,778		11,751
Postretirement Health Coverage [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		320		354	$ 415
U.S. Common Stock | Level 1 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1],[2]	6,480
U.S. Common Stock | Level 2 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1],[2]	9
Fixed Income Securities [Member] | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[3]	316		308
Fixed Income Securities [Member] | Level 1 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[3]	316
Fixed Income Securities [Member] | Level 2 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[3]	0
Fixed Income Securities [Member] | Level 3 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[3]	0
Mortgage-backed Securities, Issued by Private Enterprises [Member] | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	187		207
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Level 1 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	0
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Level 2 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	187
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Level 3 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	0
US Government Agencies Debt Securities [Member] | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	1,173		1,181
US Government Agencies Debt Securities [Member] | Level 1 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	0
US Government Agencies Debt Securities [Member] | Level 2 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	1,173
US Government Agencies Debt Securities [Member] | Level 3 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	0
Corporate Bond Securities [Member] | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	3,012		3,191
Corporate Bond Securities [Member] | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	453		439
Corporate Bond Securities [Member] | Level 1 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	0
Corporate Bond Securities [Member] | Level 1 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	0
Corporate Bond Securities [Member] | Level 2 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	3,012
Corporate Bond Securities [Member] | Level 2 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	453
Corporate Bond Securities [Member] | Level 3 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	0
Corporate Bond Securities [Member] | Level 3 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4]	0
Government Securities | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4],[5]	432		$ 433
Government Securities | Level 1 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4],[5]	0
Government Securities | Level 2 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4],[5]	432
Government Securities | Level 3 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[4],[5]	$ 0
Corporate Bonds
Defined Benefit Plan Disclosure [Line Items]
Representation of one fund in total U.S. plan assets		22.00%		23.00%
Contracts With Insurance Companies | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1],[6]	$ 7		$ 7
Contracts With Insurance Companies | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[6]	35		32
Contracts With Insurance Companies | Level 1 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1],[6]	0
Contracts With Insurance Companies | Level 1 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[6]	0
Contracts With Insurance Companies | Level 2 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1],[6]	0
Contracts With Insurance Companies | Level 2 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[6]	0
Contracts With Insurance Companies | Level 3 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1],[6]	7
Contracts With Insurance Companies | Level 3 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[6]	35
Cash And Cash Equivalents | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1]	196		267
Cash And Cash Equivalents | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		12		12
Cash And Cash Equivalents | Level 1 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1]	196
Cash And Cash Equivalents | Level 1 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		12
Cash And Cash Equivalents | Level 2 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1]	0
Cash And Cash Equivalents | Level 2 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		0
Cash And Cash Equivalents | Level 3 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1]	0
Cash And Cash Equivalents | Level 3 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		0
Sub-Total U.S. Plan Assets | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1]	11,064		10,962
Sub-Total U.S. Plan Assets | Level 1 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1]	6,676
Sub-Total U.S. Plan Assets | Level 2 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1]	4,381
Sub-Total U.S. Plan Assets | Level 3 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1]	7
Real Estate Funds [Member] | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[5]	651	[1]	735
Real Estate Funds [Member] | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[5]	84		100
Sub-Total International Plan Assets | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		2,804		2,716
Sub-Total International Plan Assets | Level 1 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		1,856
Sub-Total International Plan Assets | Level 2 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		913
Sub-Total International Plan Assets | Level 3 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		35
Dividends And Interest Receivable | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[1]	63		54
Dividends And Interest Receivable | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		6		7
Equity Securities [Member] | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		6,489	[2]	6,109
Equity Securities [Member] | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		1,556	[2]	$ 1,492
Equity Securities [Member] | Level 1 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[2]	1,528
Equity Securities [Member] | Level 2 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[2]	28
Equity Securities [Member] | Level 3 | U.S. Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		0
Equity Securities [Member] | Level 3 | International Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	[2]	$ 0
Large-Cap Fund(s) In U.S. Commingled Funds
Defined Benefit Plan Disclosure [Line Items]
Representation of one fund in total U.S. plan assets		19.00%		18.00%

[1] 2016 and 2015 amounts include $320 million and $354 million, respectively, of retiree medical plan assets that are restricted for purposes of providing health benefits for U.S. retirees and their beneficiaries.

[2] The equity securities portfolio was invested in U.S. and International common stock and commingled funds, and the preferred stock portfolio in the U.S. was invested in domestic and international corporate preferred stock investments. The common stock is based on quoted prices in active markets. The U.S. commingled funds are based on fair values of the investments owned by these funds that are benchmarked against various U.S. large, mid-cap and small company indices, and includes one large-cap fund that represents 19% and 18% of total U.S. plan assets for 2016 and 2015, respectively. The international commingled funds are based on the fair values of the investments owned by these funds that track various non-U.S. equity indices. The preferred stock investments are based on quoted bid prices for comparable securities in the marketplace and broker/dealer quotes in active markets.

[3] Based on the fair value of the investments owned by these funds that track various government and corporate bond indices.

[4] These investments are based on quoted bid prices for comparable securities in the marketplace and broker/dealer quotes in active markets. Corporate bonds of U.S.-based companies represent 22% and 23% of total U.S. plan assets for 2016 and 2015, respectively.

[5] The real estate commingled funds include investments in limited partnerships. These funds are based on the net asset value of the appraised value of investments owned by these funds as determined by independent third parties using inputs that are not observable. The majority of the funds are redeemable quarterly subject to availability of cash and have notice periods ranging from 45 to 90 days.

[6] Based on the fair value of the contracts as determined by the insurance companies using inputs that are not observable. The changes in Level 3 amounts were not significant in the years ended December 31, 2016 and December 26, 2015.